Genetically Diverse, Extremely Resistant, and Pan-drug Resistant Pseudomonas aeruginosa as the Main Cause of Nosocomial Infection Among Hospitalized Patients

Background: Clinical strains of Pseudomonas aeruginosa possess a wide diversity of antibiotic resistance and genetic characteristics. Objectives: This study aimed to determine the antibiotic susceptibility patterns and genotypes of P. aeruginosa isolated from patients with nosocomial infections. Methods: We tested 149 samples for P. aeruginosa isolation, confirmed by PCR. The Multi, Extensively, and Pan-drug resistant strains were detected through CLSI guidelines. All isolates were subjected to ERIC-PCR genotyping using specific primers. The antibiotic patterns and ERIC types were analyzed statistically using specific software. Results: Seventy-six (51%) isolates were confirmed as P. aeruginosa. Among them, 86.8% were determined as MDR, 81.5% as XDR, and 5.3% as PDR. Eight E-types were detected, which belonged to two main clusters with a similarity rate of over 70%. Cluster B, composed of E-types G and H, was a dominant cluster. Interestingly all of these cluster members were isolated from the internal ICU, and we can claim that at least two different colons had been colonized in the internal ICU. Moreover, four PDR strains were detected in this study, three of which possessed E-type G, and the remaining belonged to E-type H. Conclusions: Some unique E-types were dominant in ICUs with high diversity in antibiotic resistance patterns, which can be assumed as causative agents for nosocomial infection. The main threat here is regarding the PDR strains. They could be considered nosocomial pathogens and should be deliberated as a critical threat in an emerging hospital outbreak.